On the way to visit Shun (Soran Tamoto), who didn't attend class, Hiroshi (Taishi Nakagawa) and Anna (Yuna Taira) are drawn by a mysterious butterfly and enter the big house “Jail House”. They get lost and wander around the house. Meanwhile, Takuro (Shota Matsushima), Mika (Ikumi Hisamatsu) and Takeshi (Reo Kanshuji), who bullies Shun, enter the “Jail House” to test their courage.